Preparation And Properties Of Amino Acid/gelatin Modified HAP Bone Tissue Engineering Materials

Bone tissue engineering is a technology which built on tissue engineering principles,it devotes to regenerate new bone tissue to repair or replace bone defects or enhance bone tissue function.Currently,the focus of bone tissue engineering research is to prepare a kind of scaffold which can promote cell growth and new bone tissue regeneration.HAP has good biocompatibility,bioactivity and bone conductivity,etc.Which can be used as tissue engineering scaffold material excellently.The inorganic phase in natural bone was nano hydroxyapatite,and the organic phase in natural bone was mainly collagen,collagen accounts for about 20%to 30%of natural bone.From the perspective of biomimetic mineralization,amino acids and gelatin were used to modify and improve the surface activity and biodegradability of HAP.The composition and structures of modifier HAP was investigated.On this basis,modified hydroxyapatite porous bone tissue engineering scaffolds were prepared by extrusion molding method,which can meet the requirements of bone tissue engineering.The composition,structure,mechanical properties and biological properties were investigated and the results were shown as follows.First,four different organic modified Nano-HAP composite powders were prepared by co-precipitation method.The composition and structures of prepared composite powders were characterized by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),transmission electron microscopy(TEM);the inorganic phase in modified Nano-HAP was carbonated HAP,and the organic phase in modified Nano-HAP was amino acids or gelatin,without other hetero phase formation;modified HAP particles agglomerate as a beam distribution,the structure of particles were short rod-likes,the diameters of particles were 6nm-20nm,the length of particles were 50nm-280nm.The particles have high aspect ratio.The chemical compositions and microstructures of modified HAP were similar to the HAP in natural bone.The material cytotoxicity analysis proved that the composite powders were non toxicity.Further,honeycomb porous scaffolds which made from the composite powders as raw materials and gelatin as adhesive were prepared by extrusion molding method.The prepared scaffolds had through-hole structures.The diameter of the through-hole is 400?m-550 ?m,the diameter structure of the holes were conducive to transmission of bone tissue nutrients and material's osteoconduction.The porous scaffolds have high mechanical strength and biodegradability,as well as non toxicity.In order to increase the porosity and biological properties of porous scaffolds,stearic acid microspheres were used as pore-forming agent to prepare HAP/Gly and HAP/Gelatin porous scaffolds.The porosity of porous scaffolds were effectively increased,which increased to 70%-77%from 51%-59%;The structure of the porous scaffolds were irregularly combination of straight-hole and three-dimensional hole;The diameters of the porous scaffolds were 80?m-550?m,the diameter structure of the porous scaffolds can facilitates bone tissue ingrowth,and impart materials osteoconduction;Meanwhile,the mechanical strength of porous scaffolds were still high enough:the axial compressive strength of porous scaffolds were 13 MPa-18 MPa,and the radial compressive strength of porous scaffolds were 6 MPa-8 MPa,which can meet the bone tissue engineering demand;In degradation test,a large number of flaky HAP can deposit on the porous scaffolds,the porous scaffolds are proved to have good bioactivity and biodegradability,as well as non toxicity.The prepared modified Nano-HAP composite powders and bone tissue engineering scaffolds in this paper all exhibited good biological performance,which can be used in bone tissue engineering fields.